title: Inverse correlation between Thr-669 and constitutive tyrosine phosphorylation in the asymmetric epidermal growth factor receptor dimer conformation.
abstract: We have recently identified tumor necrosis factor (TNF)-α-induced phosphorylation of epidermal growth factor receptor (EGFR) at Thr-669 and Ser-1046/1047 via ERK and p38 pathways, respectively. In the present study, we investigated the roles of ligand-induced phosphorylation of serine and threonine residues in EGFR-overexpressing MDA-MB-468 breast cancer cells. Epidermal growth factor and heregulin, an ErbB3 ligand, induced the phosphorylation of Thr-669 and Ser-1046/1047. Inversely, constitutive tyrosine phosphorylation of the C-terminal domain, including Tyr-1068, was significantly downregulated on ligand stimulation. Inhibition of the ERK pathway by U0126 blocked ligand-induced Thr-669 phosphorylation as well as Tyr-1068 dephosphorylation. Downregulation of constitutive tyrosine phosphorylation of EGFR in HEK293 cells stably expressing the wild type was abolished by substitution of Thr-669 for Ala. In an asymmetric EGFR homodimer structure, one Thr-669 in the receiver kinase of the dimer was involved in downregulation. Similarly, Thr-669 in an EGFR-ErbB3 heterodimer also participated in tyrosine dephosphorylation. These results indicate that ERK-mediated Thr-669 phosphorylation suppresses constitutive tyrosine phosphosphorylation in the homo- and heterodimer asymmetric conformations of the EGFR.
authors.affiliation: Division of Pathogenic Biochemistry, Institute of Natural Medicine, University of Toyama, Toyama, Japan.
authors.forename: Kanae
authors.initials: K
authors.lastname: Sato
authors.forename: Myoung-Sook
authors.initials: MS
authors.lastname: Shin
authors.forename: Ayaka
authors.initials: A
authors.lastname: Sakimura
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhou
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Miho
authors.initials: M
authors.lastname: Kawanishi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kawasaki
authors.forename: Satoru
authors.initials: S
authors.lastname: Yokoyama
authors.forename: Keiichi
authors.initials: K
authors.lastname: Koizumi
authors.forename: Ikuo
authors.initials: I
authors.lastname: Saiki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology; D001943:Breast Neoplasms / Q000201:enzymology; D002070:Butadienes / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000201:enzymology; D019281:Dimerization; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000737:chemistry / Q000378:metabolism*; D025461:Feedback, Physiological; D005260:Female; D006801:Humans; D008024:Ligands; D020935:MAP Kinase Signaling System; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D020890:Neuregulin-1 / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D010769:Phosphothreonine / Q000378:metabolism*; D011487:Protein Conformation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D002070:Butadienes; D008024:Ligands; C094131:NRG1 protein, human; D009363:Neoplasm Proteins; D020890:Neuregulin-1; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; C113580:U 0126; D010769:Phosphothreonine; D004815:Epidermal Growth Factor; C512478:EGFR protein, human; D066246:ErbB Receptors